Loud 'airy' Sound On Boost

[Baconer]

Well this is a problem i've had for a few weeks now (2 weeks after installing turbo back exhaust (3" BATMBL split dump, cat and HKS silent high power)) and with an upcoming Dyno Day i want to get it fixed.

Car is pretty much stock except for the previously mentioned turbo back exhaust

Basically what has started occurring is a very loud "sssssssssshhhhhhhhhhhhhh' sound when the car hits boost causing very little power to be made, spooling up is fine but as soon as the gauge reads above 0psi its makes that ungodly noise. Have been advised it could be the wastegate being stuck open/ broken spring but wanted a second opinion or possible other causes (leaks, faulty gasket on dump pipe etc.)

Second problem is to do with the accelerator/throttle cable, I noticed today when i was searching around for any major leaks that may be causing the previous problem that my accelerator cable has a lot of slack in it. Also possibly related is my car takes off like an automatic, in that in 1st gear if i take my foot off the clutch at a stand still it will begin accelerating and picks up speed till it reaches 1,500rpm.

Thanks for any help

Alex

[Munkyb0y]

re: automatic take off. how high is your idle? i would expect it to stall if it was idling at 700rpm (factory spec)

[zertek]

put some detergent and water in a spray bottle, spray all your air flow pipe joins then boost it, best done on a dyno as u can get it to spool with out the car moving.... That should determine your leaking problem if thats what it actually is (You'll see it bubbling up at the leak), if its the wastegate, best option is having it inspected in a workshop in my opinion.

[FLY-4DR]

if it doesnt rev ou then its a Cut in piping...and when under vacume is fine....only opens up when boosted..letting air out...

[Baconer]

re: automatic take off. how high is your idle? i would expect it to stall if it was idling at 700rpm (factory spec)

it idles at 1500 warm (close to 2000 on cold start) I know its something to do with the IACV and plan on taking it off and inspecting first chance i get. Was unsure if the auto take off was unrelated to the high idle though. Would explain why it only revs to 1500 without foot on accelerator in 1st.

zertek - how would i determine if its the wastegate as ive already checked a few of the minor rubber pipes

fly-4dr - What do you mean by rev out?

[zertek]

it idles at 1500 warm (close to 2000 on cold start) I know its something to do with the IACV and plan on taking it off and inspecting first chance i get. Was unsure if the auto take off was unrelated to the high idle though. Would explain why it only revs to 1500 without foot on accelerator in 1st.

zertek - how would i determine if its the wastegate as ive already checked a few of the minor rubber pipes

fly-4dr - What do you mean by rev out?

when you say checked, did u actually use the soapy water trick? you may be suprised and find some leaks u didnt know u had. I certainly did.

Get the waste gate inspected at a workshop as its something i recommend not f**king around with unless your experienced.

[Baconer]

Haha i wouldnt be surprised, have had the same piece of piping (connects from aac to boost 'reader' (that little black box)) split atleast 3 or 4 times on both ends and its starting to go again, running out of pipe

Will give the soapy water trick a go next weekend.

I'll take the car in to my mates work next week and see what he says, will just avoid hitting boost till then, all highway driving anyway so shouldn't be too hard

[Munkyb0y]

it idles at 1500 warm (close to 2000 on cold start) I know its something to do with the IACV and plan on taking it off and inspecting first chance i get. Was unsure if the auto take off was unrelated to the high idle though. Would explain why it only revs to 1500 without foot on accelerator in 1st.

1500 is too high. specs say 700rpm warm

adjust your idle screw on the side of the aac. since it's not hunting, and cold start is about 500 higher than warm idle, it sounds like it's working ok.

i'd say it just needs to be adjusted lower.

[TTT]

if this happened after you did the exhaust change, then I'd say that maybe you haven't tightened the bolts on the back of the turbo enough, thye have got a little lose and now blown through the exhaust gasket causing a loud scream when boost gets up there..

[The Mafia]

my turbo was making a loud screeching noise and this was because the Turbo to manifold bolts came loose and was blowing through the gaskets.

[Baconer]

Well i finished work early today and spent the past 3 hours checking some things out under and around the car, tightening bolts and reattaching pipes. Found 5 pipes with holes/splits or pipes which were starting to come off, fixed them all and revs dropped from 1500 warm to 1100. There is still a hissing sound though and its from a pipe near the fuel rail, cant pick which one but im just going to replace all the rubber tubing anyway, sick of these dam vac leaks, seems to happen atleast once a month

Munkyboy - whenever i adjust the screw on AAC to lower revs it causes the car to shake, as in sitting in the drivers seat you get pushed side to side. Raising the revs with screw gets rid of this problem though. My guess is the screw is set right but another leak vac leak is causing the idle to be a bit higher then normal

GTST and Mafia - That was the other thing i had a look at and that looks to be the answer, the gap is on the underside, the shop that fixed the exhaust for me (had to modify hangers) mustn't of tightened the 2 bottom bolts, makes sense, was about 2 weeks after i installed the exhaust that i took it to the shop for a few parts to be fixed... Dunno why that didnt click earlier :X

Cheers for the help

[JustinP]

Well i finished work early today and spent the past 3 hours checking some things out under and around the car, tightening bolts and reattaching pipes. Found 5 pipes with holes/splits or pipes which were starting to come off, fixed them all and revs dropped from 1500 warm to 1100. There is still a hissing sound though and its from a pipe near the fuel rail, cant pick which one but im just going to replace all the rubber tubing anyway, sick of these dam vac leaks, seems to happen atleast once a month

Munkyboy - whenever i adjust the screw on AAC to lower revs it causes the car to shake, as in sitting in the drivers seat you get pushed side to side. Raising the revs with screw gets rid of this problem though. My guess is the screw is set right but another leak vac leak is causing the idle to be a bit higher then normal

GTST and Mafia - That was the other thing i had a look at and that looks to be the answer, the gap is on the underside, the shop that fixed the exhaust for me (had to modify hangers) mustn't of tightened the 2 bottom bolts, makes sense, was about 2 weeks after i installed the exhaust that i took it to the shop for a few parts to be fixed... Dunno why that didnt click earlier :X

Cheers for the help

Sound like the noise that comes from my car. Mine also seems to come from the drivers side. Mine does not seem to affect performance though. I've just gotten used to it :laughing-smiley-014: although I suddenly realise just how loud it is when I'm driving through a tunnel or along a wall when I put my foot down.

[Munkyb0y]

Munkyboy - whenever i adjust the screw on AAC to lower revs it causes the car to shake, as in sitting in the drivers seat you get pushed side to side. Raising the revs with screw gets rid of this problem though. My guess is the screw is set right but another leak vac leak is causing the idle to be a bit higher then normal

i'd say you're right. sounds like more air is coming in than what the aac is regulating. i.e vaccum leak

check all the vaccum hoses around the plenum for starters. replace it all with silicone hose if you have to.